This invention relates in general to automatic pistols, and in particular, provides a sub-caliber conversion unit for double-action automatic pistols of the breech block type.
Automatic pistols of this type conventionally include a frame, a barrel, and a breech block, or slide. The breech block is reciprocally mounted on the upper portion of the frame of the pistol and houses a recoil spring. A locking mechanism selectively locks the slide to the barrel at the time of firing. A magazine is mounted in a handle or grip portion of the frame, for storing cartridges.
Upon firing, the barrel and slide recoil backward in coupled connection for a short distance. The locking mechanism then disconnects the barrel from the slide, allowing the slide to continue its rearward movement against the force of the recoil spring. As the slide moves backward, it cocks a firing mechanism and actuates an extractor and ejector, for respectively extracting and ejecting the spent cartridge from the receiver. When the recoil spring is fully compressed, it pushes the slide forward, causing a cartridge to be pushed off the top of the magazine stack and into the chamber of the barrel. As the slide approaches its initial forward position, the slide re-engages with the barrel.
In the conventional Colt Government Model .45 caliber pistol, the barrel is connected to the slide by locking lugs and is held in place by the force of the recoil spring. The barrel engages the frame by means of a pivoting link. In contrast, in the Smith & Wesson Model 645, no barrel link connects the barrel to the frame Instead, the barrel rides on an inclined plane machined into the frame. Upon recoil, the rear part of the barrel is pulled downward and out of engagement with the slide by the action of mating ribs on the frame and corresponding ribs on the lower surface of the barrel.
A number of sub-caliber conversion systems have been developed for the Colt Government Model .45 caliber automatic pistol. The following U.S. Pat. Nos. disclose examples of such systems:
______________________________________ 2,090,657 Williams 2,872,050 Davenport 2,898,693 Ruger 3,504,594 Greeley 3,724,326 Day 4,253,377 Arnett ______________________________________
The Williams patent discloses a sub-caliber conversion unit for the Colt Government Model .45 automatic pistol, including a sub-caliber barrel, ejector, extractor, slide and magazine. Williams also discloses a chamber member for increasing sub-caliber recoil to approximate the perceived recoil of the standard .45 caliber cartridges.
The Davenport patent discloses a sub-caliber device for the Colt .45 pistol, including a sub-caliber barrel and chamber unit which floats within a sleeve affixed to the frame of the firearm.
The Ruger patent discloses a sub-caliber conversion for the Colt .45 pistol, including a .22 caliber barrel which is operatively affixed to the frame of the firearm, a breech block receiver which engages the frame in the same manner as the original slide but which is secured in its operative position to the barrel and indirectly to the frame, and a blow-back breech block mounted in the receiver. A sub-caliber magazine is also disclosed.
The Greeley patent discloses a sub-caliber conversion unit for a Colt .45 automatic pistol, including a barrel having a depending block formed with a downward and rearward sloping slot which engages a pivot pin 28, so that the barrel upon firing is tilted and unlocked from the slide to effect operation of the extractor.
The Day patent discloses a sub-caliber conversion unit adapted to be detachably secured to and firmly supported by the lower receiver group of a larger caliber pistol such as the Colt .45 caliber automatic pistol, wherein the slide of the conversion unit operates independently of the barrel. A sub-caliber magazine insert is also disclosed.
The Arnett patent discloses a sub-caliber conversion for an automatic pistol such as the Colt Government Model .45, including a sub-caliber barrel mounted in the slide and detachably connected to the frame by a pivotal link A sub-caliber magazine is disclosed, and a cambered, semi-flexible extracter is utilized to capture and extract cartridges of both the larger caliber and the sub-caliber.
Each of the above patents describes sub-caliber conversions for the Colt Government Model .45 caliber automatic pistol. However, no device or system previously in existence provides a sub-caliber conversion for the Smith & Wesson Model 645 .45 automatic pistol, with its inclined plane barrel-locking system entirely different from that of the Colt Government Model Moreover, existing sub-caliber conversion systems require numerous parts changes or modifications to the larger caliber pistol, including changes to the slide, extractor, ejector, recoil spring, hammer spring (or mainspring) and magazine, a well as to the barrel. There accordingly exists a need for a simple, inexpensive sub-caliber conversion unit for Smith & Wesson Model 645 .45 automatic pistols and the like.
It is thus an object of the invention to provide a sub-caliber conversion unit for the Smith & Wesson Model 645 .45 automatic pistol.
It is another object of the invention to provide a Smith & Wesson Model 645 sub-caliber conversion unit which is inexpensive, requires a minimum of modifications or new parts for the larger caliber pistol, is simple to install and remove, and which maintains high accuracy levels.
It is a further object of the invention to provide a magazine for a Smith & Wesson Model 645 sub-caliber conversion unit which can accommodate cartridges of both the larger caliber and the sub-caliber.
It is yet another object of the invention to provide a magazine for a Smith & Wesson Model 645 sub-caliber conversion unit which can accommodate rimmed cartridges such as .38 Special.
Other general and specific objects of the invention will in part be obvious and will in part appear hereinafter.